Small-strain stiffness and deformation behavior of cation crosslinked-xanthan gum treated sand

Abstract

Crosslinked xanthan gum (CrXG) has been introduced to enhance the mechanical stability of biopolymer–soil composites under hydrated conditions. However, its effects on the small-strain stiffness and deformation behavior of granular soils remain underexplored. This study examines the evolution of small-strain shear stiffness, vertical deformation behavior, and shear wave velocity (Vs) in CrXG-treated soils using bender element testing. The results indicate that CrXG treatment improves shear stiffness through a time-dependent gel stiffening mechanism. Higher CrXG concentrations yield greater initial stiffness, with stabilization occurring after approximately 7 days. Additionally, the vertical deformation behavior of CrXG-treated soils is stress-dependent. Increased CrXG concentrations lead to higher Vs values, an elevated α-factor, and a reduced β-exponent, trends that are comparable to those observed in cemented soils. These effects are attributed to the formation of an intergranular hydrogel matrix that enhances particle bonding. These findings provide insights into the mechanical behavior of CrXG-treated soils and their potential applications in geotechnical engineering, particularly for improving soil stiffness and stability.